1. Field of the Invention
The present invention relates to an automatic discharge apparatus for an electrostatic chuck used in a semiconductor manufacturing facility, and more particularly, to an automatic discharge apparatus that is capable of completely discharging any residual charge remaining on an electrostatic chuck after cutting off driving power to the electrostatic chuck.
2. Discussion of Related Art
An electrostatic chuck in a semiconductor facility is a stage on which a wafer is placed in order to manufacture a semiconductor device. The wafer is held securely in place during semiconductor manufacture (i.e., chucked) by voltage from a power supply unit.
After certain processes are performed on the wafer, the wafer must be moved to a different area or different piece of equipment to execute another process. In such cases, the driving power supplied for chucking the wafer should be intercepted, thereby allowing the wafer to be separated from the electrostatic chuck for transfer to another process area.
However, even though the driving power to the electrostatic chuck is intercepted or cut off, the wafer is not completely released due to the residual voltage remaining on the electrostatic chuck. Therefore, before the residual voltage is discharged, if an operator or piece of equipment tries to manually or automatically move the wafer, the residual voltage causes the wafer to xe2x80x9creboundxe2x80x9d, or be attracted back to the chuck, thereby causing the wafer to break or slip within the processing chamber.
The resulting breakage introduces foreign matter into the processing chamber, which decreases the device yields. Moreover, if wafer breakage or slippage occurs, time is lost in removing and cleaning the processing chamber, which reduces the productivity of the processing line. The decreases in both yields and productivity eventually increases the cost of manufacturing the semiconductor devices.
Accordingly, the present invention is directed to an automatic discharge apparatus for an electrostatic chuck used in a semiconductor manufacturing facility that substantially overcomes one or more of the limitations and disadvantages of the related art.
A primary object of the present invention is to provide an automatic discharge apparatus for an electrostatic chuck which is capable of completely discharging the residual voltage remaining on an electrostatic chuck after the driving power to the electrostatic chuck is cut off, thereby preventing wafer breakage or slippage during semiconductor manufacture.
Another object of the present invention is to provide an automatic discharge apparatus for an electrostatic chuck which is capable of increasing the operating capacity and yields of a semiconductor manufacturing facility.
To achieve these and other advantages, and in accordance with the purpose of the present invention, an automatic discharge apparatus for an electrostatic chuck includes a high voltage determining part having an external high voltage determination value supplied thereto; a high voltage generating transformer, electrically connected to an output of the high voltage determining part, for generating the high voltage to be supplied to an electrostatic chuck under control of the high voltage determining part; a high voltage controlling part, electrically connected to the high voltage generating transformer and the electrostatic chuck, for controlling the high voltage supplied from the high voltage generating transformer to the electrostatic chuck in response to an on/off state of power supplied by a power supply; and a discharge circuit part electrically connected between the electrostatic chuck and the power supply for forcibly discharging residual voltage remaining on the electrostatic chuck in response to an off state of the power supply.
It is desirable that the high voltage controlling part comprises a high voltage controlling relay for connecting respective output terminals of the high voltage generating transformer with a positive voltage terminal and a negative voltage terminal of the electrostatic chuck.
In addition, a residual voltage detecting part is connected to the positive voltage terminal of the electrostatic chuck, and when the power of the electrostatic chuck is cut off, detects the residual voltage of the electrostatic chuck and provides it to a monitor.
The discharge circuit part includes a discharge relay interlocked with a driving power on/off state of the electrostatic chuck, and connects the positive voltage terminal and the negative voltage terminal of the electrostatic chuck to a discharging element. The discharging element is connected to both the positive voltage terminal and the negative voltage terminal of the electrostatic chuck by way of the discharge relay, the discharging element being for discharging the residual voltage remaining in the electrostatic chuck. The discharging element may comprise a neon lamp.